Immunity is one of self-protection systems in vivo against all external polymers (antigens) which are invaded or injected into tissues. A lymphocyte as a major component of an immune system is a leukocyte which is generated in the bone marrow and circulated in a lymph tissue or organ, particularly, a lymphatic node, a spleen, and onsil along the blood. As cells involved in an immune response, B cells are rapidly proliferated when being stimulated by a proper antigen to form a clone which makes a specific antibody (immunoglobulin) for neutralizing the antigen and the antibody made by the B cell performs the humoral immunity while circulating in the body fluid. Further, T cells are generated in the thymus to move to a lymphatic tissue and are responsible for cell-mediated immunity to directly attack the antigen.
Meanwhile, in all normal objects, one of the important features has ability capable of detecting, respond, and removing many non-self antigens without harmfully responding to self-antigen substances. As such, non-response to the self-antigen of the living body is called immunologic unresponsiveness or tolerance.
When a problem is caused in inducing or continuously maintaining the self-tolerance, the immune response to the self-antigen occurs. As a result, a phenomenon in which the self-antigen attacks the self-tissue occurs to cause autoimmune diseases such as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, and Hashimoto's thyroiditis and cause immune rejection after a surgical procedure such as transplantation.
In detail, since the autoimmune disease is a disease caused by abnormal response to self-cells, drugs which suppress an autoimmune function have been mainly used for treatment. However, the drugs have many side effects to be difficult to be continuously used and do not sufficiently prevent a recurrence to have a limit in the treatment for a full recovery. In the case of multiple sclerosis, beta interferon is used, but the beta interferon has expensive treatment cost instead of less side effects and inconvenience in that an injection is required during life, and has a slight effect of preventing the recurrence. Further, a method of inhibiting interaction between cells by administrating an antibody to a CD40 ligand has been used, but is not so successful. Other many immune therapies are included, but there is yet no case admitted as a method which exhibits clear therapeutic efficacy.
Accordingly, the autoimmune disease may be efficiently treated and researches of therapeutic agents which are harmless to the human body and have no side effect are required.